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LiPo VS. NiMh ??

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Old 05-29-2009, 02:06 AM
  #1
Rodx
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Default LiPo VS. NiMh ??

Hi !

First thing : I'm french and I'm sorry for my poor english... Hope you'll understand...

I own an E-Firestorm since few months and I just bought an EZrun combo (5.5T/60A). And now Ineed to change my batteries and my charger. But... I don't really know if I must choose LIPO ones or NiMh ones ?...
Could you please help me to make my choice? It's probably a stupid question but I'm new in the "RCWorld" and I don't really know what are the real differences between these 2 kind of batteries...

Thanks in advance...
Rodolphe (from France)
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Old 05-29-2009, 08:47 AM
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Jeremy Z
 
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Default RE: LiPo VS. NiMh ??



The chemistry is different.



Here's a quick breakdown:



LiPos hold a charge much, much better on the shelf. They will hold a charge for months without noticable loss.



LiPos are half as heavy for a given capacity



LiPos are fragile compared to NiMH. If you get one without a hard case and you dent it, it will likely be ruined. If you try to charge it, it may burst into flames. It happened to my dad, nearly burned down his house. Good thing he was charging it in a glass baking dish. He said it shot out a green flame about a foot long.



For a given quality level, LiPos are more expensive.



LiPos need to be manually balanced; they don't automatically balance during charging like nickel cells do.



To me, the bottom line is that I don't feel like I have to keep an eye on NiMH while charging, and for LiPos, I do.

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Old 05-29-2009, 08:55 AM
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Default RE: LiPo VS. NiMh ??

Wow ! I think I'll choose NiMH ones...
Thanks JeremyZ !

Rodx
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Old 05-29-2009, 09:05 AM
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Default RE: LiPo VS. NiMh ??

If you never try lipo, you will never see what electrics are truly capable of. Yes, you have to be a little more vigilant in how you maintain and use them, but the performance trade off is far superior IMO. There are countless users who use lipos on a regular basis and never have a problem (including me).
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Old 05-29-2009, 09:25 AM
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Default RE: LiPo VS. NiMh ??

NiMh seems to be easier to deal with, but as I've started using LiPo, I really like it.  Here are some interesting tidbits of info:

    [*]You can charge a LiPo weeks in advance of using, and it will hold that charge.  No need to "top it off" like NiMh that drain over time.  I love this feature, as I don't run/charge every day, so won't have the urge to run down and "top off" the NiMh before running.[*]LiPos require some "hidden cost" items that folks may not think of when just pricing a LiPo battery vs. a NiMh one:
      [*]Charger needs to be LiPo capable.[*]If the charger doesn't have a built in balancer, you need to buy one (like the AstroFlight Blinky) - very easy to use, though.[*]Your ESC needs a low-voltage cutoff (LVC) with LiPo.  If you discharge LiPo too far (i.e., run it until it won't go, without an LVC), you damage it.  Some (higher end/newer) ESCs have LVC built in (most BL ones will), but most inexpensive brushed ESCs do not - so you have to buy an LVC to wire in.[*]Some folks buy a LiPo sack to charge in, to be extra safe.[/list][*]LiPos all have ratings you need to pay attention to - discharge rating (15C, 25C, etc) in conjunction with capacity (5000 mAh, etc).  For 1/10 buggies, you don't need big beefy 30C batteries (what...15C will do?).  But for a 1/10 or 1/8 MT (heavier, more powerful systems), you have to have that high C rating (25C, 30C+) to be sure the batteries can handle the big honkin' brushless motor you may be powering that system with.[/list]Personally, I own both - but want to switch over to LiPo.  You just need to read up more on LiPo as a beginner to be sure you know all you need to know - make sure you do things right. 
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Old 05-29-2009, 10:05 AM
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Default RE: LiPo VS. NiMh ??

IMHO you should go for LiPos as they pack more punch and hold their charge well even after few weeks unlike NiMh.
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Old 05-29-2009, 03:42 PM
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Default RE: LiPo VS. NiMh ??

on the nimh side of things, they are of course much more stable but when it comes to speed and long runtimes the lipos and even li-ions have nimhs beat hands down, i will say that for racing, i can and have beat guys using lipos in there 1/10 st's with high end nimg packs in my car but in those cases it came down to setup but for bashing and speed runs lipos are king, also, with ANY battery you should take care of it. as long as you dont do really stupid stuff, and take care of your packs, and avoid damage you should never have any real issues.
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Old 05-29-2009, 04:01 PM
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Default RE: LiPo VS. NiMh ??



All of the stuff said above is true. But there are more things to think about with LiPo.



It is hard to make a blanket statement about LiPos giving more power than NiMH. A good quality, 3600 mAh NiMH, 6 cell pack goes for around $25.



Do you think a $25 LiPo will match the performance and longevity of the good quality NiMH? It is hard to tell.



It is worth noting that a LiPo doesn't have to perform as well as the same rating NiMH, because it weighs half as much.



In Fieroman's case, there are too many factors to point to the battery. Maybe he is just a much better driver? Maybe the weight of the battery makes his tires grip better? Maybe it is some other set-up issue?



Most people here would suggest to start with NiMH, (you already have enough to think about!)  and invest a bit more in a charger that will handle LiPo if you decide to go that route in the future.



After you have a couple NiMH packs and you've got your mind wrapped around this whole thing, try a LiPo.



There's one guy (might've been Eman) who had a fire start with a cheap NiCd battery pack. They only way that would happen is either a bad connection generating heat, or a bad cell effectively making a 6 cell pack into a 5 cell, and the charger still charging as if it were 6.



Here are a couple of ways you can screw up with LiPos:



- If you set your charger to "3S" and have a "2S" pack, it'll overcharge and burst into flames.
- If you dent the pack (they're foil-wrapped and soft, unless you get a hard case one) without noticing, then go to charge it, it can burst into flames.
- If you have the charger set for NiCd, NiMH or lead acid, and start to charge the LiPo, it can burst into flames.
- If you momentarily short any cell of the pack, (for example when soldering on a different connector or balance tap) it can be critically damaged in a short time period that a NiMH would just shrug off.



If you are lured over to the LiPo side by the promise of extra performance, lower weight, or higher power density, at least take precautions to prevent fires, such as charging them in a fireproof bag or baking dish. Just like riding a motorcycle, it is all about minimizing the risks.

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Old 05-29-2009, 06:38 PM
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Default RE: LiPo VS. NiMh ??



good point, but if precautions are taken everytime you use it the



risk factor is very low. as stated nimh and nicd can catch fire aswel



and really no batteriy should be left charging unnatended. for brushed



motor setups the difference in power maybe debateble (2s vs 6cell) but



with a brushless setup the difference is DAYand NIGHT. i was a bit scared



at the start of lipo's but i had a charger that could charge them. as long as



it is on the right setting, its as safe or easy as any other battery, just has another



plug for the balancer. i wish i had got lipo earlier. my 2c



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Old 05-29-2009, 09:08 PM
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Default RE: LiPo VS. NiMh ??



would a 2s lipo be as fast or faster as a 7 cell or 8 cell nimh pack?



im in the same rut, heres what i have rustler sw/4600 on 16/86 gearing running around 150 degrees after 10 minutes of runtime about 35mph?



heres what i want



longer run times



more speed 40ish



CONTROLLABLE POWER i run in soft dirt/ hard dirt..



if  i can get 20-25 minutes and around 40mph out of a nimh pack ill be happy





so my options are



2s lipo, 7cell promatch racing pack, 8 cell promatch racing pack, 7 or 8 cell cheapbatterypacks. com pack



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Old 05-29-2009, 10:11 PM
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Default RE: LiPo VS. NiMh ??


Quote:
ORIGINAL: Traxxas4fun



woulda 2s lipo be as fast or faster as a 7 cell or 8 cell nimh pack?
a high end 6 cell nimh pack can keep up with a 2s lipo on a track no problem, as for run times, for the most part the lipo will keep going after the nimh has already dumped.

a good nimh 6 cell pack can deffinantly keep up with a lipo for example the ones i run are rated at atleast 1.234v a cell, that .034/5/6 adds up to a good 7.41v a pack, they are also matched and zapped.

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Old 05-29-2009, 10:23 PM
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Default RE: LiPo VS. NiMh ??



so would a promatch racing 4600 pack MATCHED be as good or better than 2s lipo?



im talking speed wise

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Old 05-29-2009, 10:39 PM
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Default RE: LiPo VS. NiMh ??

invest in a good qaulity nimh pack and learn how to treat a battery before you go to lipo. as said before, get a charger that can do both. my spc 3800 6 cell spc packs are insane and more crazy r my 7 cell 4600 race packs from spc. i've owned many batteries and these are the best by a long shot Spec Point Concepts . haven't gone lipo yet but when i do i'll atleast know what to expect concerning safe use and treatment...
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Old 05-30-2009, 12:36 AM
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Default RE: LiPo VS. NiMh ??

Hey Rodx stop by the E-Firestorm thread...lots of info and some good guys with firestorms....
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Old 05-30-2009, 07:08 AM
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Default RE: LiPo VS. NiMh ??


Quote:
ORIGINAL: rhowe

my spc 3800 6 cell spc packs are insane and more crazy r my 7 cell 4600 race packs from spc. i've owned many batteries and these are the best by a long shot Spec Point Concepts . haven't gone lipo yet but when i do i'll atleast know what to expect concerning safe use and treatment...
+1000000

SPCISAWSOME!those are the packs i run, ill never buy from another brand!!!!!!
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Old 05-30-2009, 07:14 AM
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Default RE: LiPo VS. NiMh ??


Quote:
ORIGINAL: nitroade

If you never try lipo, you will never see what electrics are truly capable of. Yes, you have to be a little more vigilant in how you maintain and use them, but the performance trade off is far superior IMO. There are countless users who use lipos on a regular basis and never have a problem (including me).

very well said!!!

i made the switch recently myself and will NEVER go back
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Old 05-30-2009, 08:04 AM
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Default RE: LiPo VS. NiMh ??



no offence to you guys but i think ill buy lipos before i spend $90 on a nimh 7 cell battery..



i can get a 4000mah 2s hard case lipo for 30 bucks and a charger for 30 bucks off hobby city

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Old 06-01-2009, 04:20 AM
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Default RE: LiPo VS. NiMh ??

Lipo is the future - now. Try to buy a Nicd now. Replaced with Nimh, whitch is replaced by Lipo.The brushless will perform so much more with Lipo. Hard case Lipo's are getting cheap. And Lipo's can be charged many times per day.
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Old 06-02-2009, 07:51 PM
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Default RE: LiPo VS. NiMh ??

Before I bought my Savage Flux, I was on the fence with lipo. Well, short story short, l went with lipos and do not regret it. If you are on the fence, go lipo. These days, using lipos is foolproof provided you set your low voltage cutoff properly and charge them properly. Most all ESCs these days can be set for low voltage cutoffs and most all of today's chargers are very easy to use. 
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Old 06-02-2009, 09:26 PM
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Default RE: LiPo VS. NiMh ??

I havent read anything about AMPS. Did i miss the amperage parts, if you have a quality 6 cell nimh 4000mah with a 35 amp discharge rate or a 2 cell lipo 4000mah 20c with an 80 amp discharge rate, which do you think will perform better. The lipo will have so much more punch, grunt, whatever you want to call it, and it weighs about 60% of the minh. Hook a good 700 motor up to 8 "AA" duracells(12v), then hook it up to a 12v car battery, see which one almost spins your hand off, those are amps. I have both lipos and nimhs, i still get alot of use out of my nimhs, but the lipos make me grin.
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Old 06-02-2009, 11:25 PM
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Default RE: LiPo VS. NiMh ??

Quote:
ORIGINAL: Jeremy Z
Here are a couple of ways you can screw up with LiPos:

What you didn't mention was that if you charge a NIMHin LiPo mode, it can also explode.
Honestly most chargers are pretty safe when it comes to the 2s/3s thing too, they'll recognize the wrong voltage and stop.

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Old 06-04-2009, 02:10 AM
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Default RE: LiPo VS. NiMh ??

Hi !
Many thanks for all your answers... I think I'll choose in a first time NiMh batteries...
Could you please tell me what kind of battery I need to buy for my E-Firestorm (w/ Ezrun combo 5.5T/60A) ? And do you know good website where I could buy them ? Thanks in advance.

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Old 06-04-2009, 02:37 AM
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Default RE: LiPo VS. NiMh ??

an intelect 4600 or 4200 will get it going.
these batteries tollerate heat well too.
plenty of power and runtime.
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Old 06-04-2009, 03:14 AM
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Default RE: LiPo VS. NiMh ??

Thank you MonsterBomb !
What do you think of these ones (Intellect 4600 7.2v) : http://cgi.ebay.fr/ws/eBayISAPI.dll?...m=120420391437

Regards.
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